Ptychosperma Macarthurii
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Threatened Species of the Northern Territory DARWIN PALM Ptychosperma macarthurii Conservation status Australia: Not listed Northern Territory: Endangered Photo: S. Taylor Description than 1 km2 (Anon 1998; Liddle et al. 2001). Population counts in 2000-01 revealed adult This species is a slender clumping, feather- plants at seven locations, four of which had leaved palm with a small crown supported on fewer than 20 and the smallest with only one a narrow trunk 3 to 6 cm in diameter. adult plant. Of a total of 1037 adult plants, Flowering: May, Dec. 70% occurred in one population at Crocodile Fruiting: Aug, Sept, Nov, Dec. Creek. These counts overstate the number of mature individuals as plants were classified as Note adults on the basis of size and thus may include individuals not capable of There has been some debate over the reproduction. taxonomic status of this palm (Shapcott 1998). It was formerly considered as an NT Conservation reserves where reported: endemic, Ptychosperma bleeseri. Here, we Black Jungle Conservation Reserve follow Dixon et al. (2003) and treat P. bleeseri as a synonym and isolated population of P. macarthurii, a species more widespread in Queensland The NT entity will be treated under this latter name in the forthcoming revision in Flora of Australia (John Dowe pers. comm.). Distribution Ptychosperma macarthurii is known from the NT, Cape York Peninsula and Papua New Guinea. In the NT, this species is known from eight populations with an extent of Known locations of Ptychosperma macarthurii occurrence of 200 km2 (Duff et al. 1992; Barrow et al. 1993; Liddle et al. 1996). Within this area, it is restricted to wet rainforest patches and has an area of occupancy of less For more information visit www.denr.nt.gov.au Ecology disturbance by feral animals, sufficient small juvenile plants survived and grew to infill the This species occurs in dense rainforests intermediate classes. associated with lowland springs near the margins of riverine floodplains. The soils In addition to the above, there are increasing typically comprise deep organic clay loams threats from: changed fire regimes due to without humus development. Within the increased fuel loads from introduced grasses rainforest patches the species will grow in a around rainforest margins; wide range of light conditions (Duff et al. • changed land use in the catchment that 1992; Barrow et al. 1993; Liddle et al. 1996). could lead to a reduction in the water supply to the springs on which the Conservation assessment rainforests depend; In the NT, this species is classified as • changes in surface water quantity and Endangered (under criteria A4bce; quality; B1ab(ii,iii,iv)+2ab(ii,iii,iv); C1) based on: • clearing proposals and any other action • the small number of mature individuals; that could remove or damage individual • severely fragmented populations; and rainforest patches that form an interconnected mosaic essential for the • a past observed and a projected future flow of genetic material; and decline in population and quality of habitat. • hybridisation with introduced Ptychosperma species. Threatening processes Conservation objectives and Fire and feral animals have been the primary management threats impinging on the populations in the 1990s (Liddle et al. 1992ab, 1996, 2001, A Recovery Plan for this palm was developed 2006). There was substantial mortality in 2005 and is aimed at the long-term following wildfires at the Whitewood Road conservation of the species and its habitat. population in 1990 and 1993, and at Black The Plan addresses recovery of the wild Creek in 1992. In a 1990 survey, Whitewood populations, community involvement and Road contained 42% of the known adults, public education, land use planning, ex-situ however this was reduced to 5% by 2000- conservation, research and monitoring (Liddle 2001. Re-survey of Bankers Jungle in 2003 and Scott 2005). showed significant impacts from grazing with Priority conservation actions include: the loss of juvenile and adult plants. Disturbance from feral buffalo, cattle and pigs i. protection of the habitat from declined in the 1990s following on from the introduced animals and fire in Brucellosis and Tuberculosis Eradication conjunction with ongoing monitoring Campaign, and changes in land use and to provide feedback on the population fencing of four of the eight populations. In the response; and early 1990s, several populations exhibited a ii. research into the water supply that polarised size class structure typified by large maintains the spring-fed rainforests. adult and juvenile plants. In the absence of wildfire and in a period of reduced Page 2 of 3 Complied by Liddle, D.T., Taylor, S.M., and Larcombe, D.R. (1996). Population changes from 1990 to 1995 Raelee Kerrigan and management of the endangered rainforest Ian Cowie palm Ptychosperma bleeseri Burret (Arecaceae). Dave Liddle In: Back from the brink; refining the threatened [May 2006] species recovery process. (eds S. Stephens and S. Maxwell). pp. 110-113 (Surrey Beatty & Sons, References Sydney.) Liddle, D.T., Larcombe, D.R., and Fitzgerald P.J. Anon. (1998). A Management Program for (2001). From uncontrolled harvest to weeds and Ptychosperma bleeseri Burret in the Northern fire: an evolution of threats to the endangered Territory of Australia. (Parks and Wildlife rainforest palm, Ptychosperma bleeseri. Palms & Commission of the Northern Territory, Cycads 72, 18-25. Palmerston.) Liddle, D.T., Brook, B., Matthews, J., Taylor, S.M., Barrow, P. Duff, G., Liddle, D., and Russell-Smith, J. and Caley, P. (2006). Threat and response: A (1993). Threats to monsoon rainforest habitat in decade of decline in a regionally endangered northern Australia: the case of Ptychosperma rainforest palm affected by fire and introduced bleeseri Burret (Arecaceae). Australian Journal of animals. Biological Conservation 132, 362-375. Ecology 18, 463-471. Shapcott, A. (1998). The genetics of Ptychosperma Dixon, D., Cowie, I., and Kerrigan, R. (2003). bleeseri, a rare palm from the Northern Ptychosperma macarthurii or P. bleeseri? The Territory, Australia. Biological Conservation 85, taxonomic status of P. bleeseri reconsidered. The 203-209 Beagle 19, 81-86. Duff, G., Wightman, G., and Eamus, D. (1992). Conservation and Management of the Endangered Palm Ptychosperma bleeseri. In: Conservation and Development Issues in North Australia. (eds I. Moffatt and A. Webb). pp. 69- 77. (North Australia Research Unit, Darwin.) Liddle, D.T., and Scott, B.K. (2005). Recovery plan for Darwin Palm in the Northern Territory of Australia, 2006 to 2010. (NT Department of Natural Resources, Environment and the Arts, Darwin.) Liddle, D.T., Wightman, G.M., and Taylor, S. (1992a). Conservation Research Statement for the Palm Ptychosperma bleeseri. Report to Australian National Parks and Wildlife Service, Endangered Species Program, Project Number 159. Liddle, D.T., Wightman, G.M., and Taylor, S. (1992b) Recovery Plan for the Palm Ptychosperma bleeseri. Report to Australian National Parks and Wildlife Service, Endangered Species Program, Project Number 159. Page 3 of 3 .